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[94.113.247.30]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a80f414e069sm138126466b.178.2024.08.14.00.05.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Aug 2024 00:05:05 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Wed, 14 Aug 2024 09:05:03 +0200 To: Oleg Nesterov Cc: Ingo Molnar , Peter Zijlstra , Andrii Nakryiko , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH tip/perf/core] bpf: fix use-after-free in bpf_uprobe_multi_link_attach() Message-ID: References: <20240813152524.GA7292@redhat.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240813152524.GA7292@redhat.com> On Tue, Aug 13, 2024 at 05:25:24PM +0200, Oleg Nesterov wrote: > If bpf_link_prime() fails, bpf_uprobe_multi_link_attach() goes to the > error_free label and frees the array of bpf_uprobe's without calling > bpf_uprobe_unregister(). > > This leaks bpf_uprobe->uprobe and worse, this frees bpf_uprobe->consumer > without removing it from the uprobe->consumers list. > > Cc: stable@vger.kernel.org > Fixes: 89ae89f53d20 ("bpf: Add multi uprobe link") > Reported-by: syzbot+f7a1c2c2711e4a780f19@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/all/000000000000382d39061f59f2dd@google.com/ > Tested-by: syzbot+f7a1c2c2711e4a780f19@syzkaller.appspotmail.com > Acked-by: Andrii Nakryiko > Signed-off-by: Oleg Nesterov thanks for fixing this Acked-by: Jiri Olsa jirka > --- > kernel/trace/bpf_trace.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index 4e391daafa64..90cd30e9723e 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -3484,17 +3484,20 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr > &uprobes[i].consumer); > if (IS_ERR(uprobes[i].uprobe)) { > err = PTR_ERR(uprobes[i].uprobe); > - bpf_uprobe_unregister(uprobes, i); > - goto error_free; > + link->cnt = i; > + goto error_unregister; > } > } > > err = bpf_link_prime(&link->link, &link_primer); > if (err) > - goto error_free; > + goto error_unregister; > > return bpf_link_settle(&link_primer); > > +error_unregister: > + bpf_uprobe_unregister(uprobes, link->cnt); > + > error_free: > kvfree(uprobes); > kfree(link); > -- > 2.25.1.362.g51ebf55 > >